In multi-antenna transmission and reception systems, multiple signals are transmitted by and received by different antenna paths. Due to several factors, including machinating tolerances, network conditions, and interference, signals transmitted by different antenna paths may experience different than expected phase shifts and/or time delays leading to decrease in transceiver performance.
Calibrating the antenna paths can reduce or eliminate these differences. Antenna arrays may be calibrated using external equipment before installation. However, those methods can only be used for offline calibration, which is suitable for passive antenna arrays and not active antenna arrays.
Antenna arrays may also be calibrated using additional circuitry included with the antenna array. However, including additional circuitry may introduce additional error in calculating parameters needed for calibration. This error may increase exponentially with the number of antennas and antenna paths included in the antenna array.